After one of her nine-mile training sessions for an upcoming half-marathon, Trish Staine started to feel tremendous pain. Thinking their mom had pulled a muscle or ruptured a disc, Staine’s children called an ambulance that brought her to a local hospital in Duluth, Minn., where doctors gave her surprising news: She was pregnant and she was in labor.

By the time her husband, John, arrived, Staine had already given birth to a baby girl. Staine said she didn’t know she was pregnant. Her husband had had a vasectomy, and she did not gain weight, feel any fetal movement, or stop having her monthly periods, she told KTSP.

"In the ER, they found a fetal heartbeat. I was like, no no no. There's no way I'm pregnant. But they rushed me up to the birthing center, and five minutes after I got into my room, she was born," Staine told WDIO.

When doctors at Essentia Health-St. Mary’s Medical Center told John his 33-year-old wife had given birth, he was in denial. “Whose baby is that?” he remembers asking doctors. “It’s not possible.”

Both mother and baby are reportedly doing well. Baby Mira, short for Miracle, was born on Monday. She was five weeks early and had low blood sugar but was otherwise healthy, WDIO reports. They are expecting to go home today, the Duluth News Tribune reports.

Staine and her husband have two biological children and two foster children. Unlike with her other pregnancies, Staine had no idea she was expecting and had been training hard for a half-marathon on June 22.